.\"	$NetBSD: opendisk.3,v 1.11 2008/04/30 13:10:52 martin Exp $
.\"
.\" Copyright (c) 1997, 2001 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Luke Mewburn.
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.Dd December 11, 2001
.Dt OPENDISK 3
.Os
.Sh NAME
.Nm opendisk
.Nd open a disk partition
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In util.h
.Ft int
.Fo opendisk
.Fa "const char *path"
.Fa "int flags"
.Fa "char *buf"
.Fa "size_t buflen"
.Fa "int iscooked"
.Fc
.Sh DESCRIPTION
.Fn opendisk
opens
.Fa path ,
for reading and/or writing as specified by the argument
.Fa flags
using
.Xr open 2 ,
and the file descriptor is returned to the caller.
.Fa buf
is used to store the resultant filename.
.Fa buflen
is the size, in bytes, of the array referenced by
.Fa buf
(usually
.Dv MAXPATHLEN
bytes).
.Fa iscooked
controls which paths in
.Pa /dev
are tried.
.Pp
.Fn opendisk
attempts to open the following variations of
.Fa path ,
in order:
.Bl -tag -width "/dev/rpathX"
.It Pa path
The pathname as given.
.It Pa path Ns Em X
.Fa path
with a suffix of
.Sq Em X ,
where
.Sq Em X
represents the raw partition of the device, as determined by
.Xr getrawpartition 3 ,
usually
.Dq c .
.El
.Pp
If
.Fa path
does not contain a
slash
.Pq Dq / ,
the following variations are attempted:
.Pp
.Bl -dash -offset indent
.It
If
.Fa iscooked
is zero:
.Pp
.Bl -tag -width "/dev/rpathX"
.It Pa /dev/rpath
.Fa path
with a prefix of
.Dq Pa /dev/r .
.It Pa /dev/rpath Ns Em X
.Fa path
with a prefix of
.Dq Pa /dev/r
and a suffix of
.Sq Em X
(q.v.).
.El
.It
If
.Fa iscooked
is non-zero:
.Bl -tag -width "/dev/rpathX"
.It Pa /dev/path
.Fa path
with a prefix of
.Dq Pa /dev/ .
.It Pa /dev/path Ns Em X
.Fa path
with a prefix of
.Dq Pa /dev/
and a suffix of
.Sq Em X
(q.v.).
.El
.El
.Sh RETURN VALUES
An open file descriptor, or -1 if the
.Xr open 2
failed.
.Sh ERRORS
.Fn opendisk
may set
.Va errno
to one of the following values:
.Bl -tag -width Er
.It Bq Er EINVAL
.Dv O_CREAT
was set in
.Fa flags ,
or
.Xr getrawpartition 3
didn't return a valid partition.
.It Bq Er EFAULT
.Fa buf
was the
.Dv NULL
pointer.
.El
.Pp
The
.Fn opendisk
function
may also set
.Va errno
to any value specified by the
.Xr open 2
function.
.Sh SEE ALSO
.Xr open 2 ,
.Xr getrawpartition 3
.Sh HISTORY
The
.Fn opendisk
function first appeared in
.Nx 1.3 .
